This disclosure relates generally to invasive monitoring of arterial blood pressure of a subject. More particularly, this disclosure relates to control of alarm functionality in invasive monitoring of arterial blood pressure.
Although most blood pressure measurements are made non-invasively, invasive blood pressure measurement is used when continuous tracking of blood pressure is required and when accurate information about the waveform of blood pressure is required. Invasive blood measurement is typically used in connection with surgical procedures and in intensive care units (ICUs).
Invasive blood pressure measurement is carried out with an intravascular cannula by placing the needle of the cannula in an artery, typically in a peripheral artery. These intravenous cannulas are typically provided with a three way stopcock that allows, for example, arterial blood samples to be taken from the subject in the middle of the blood pressure monitoring process.
Upcoming international standards on invasive blood pressure measurement mandate a high priority alarm in 10 seconds if arterial pressure falls below 10 mmHg. This is because such a sudden pressure drop may be caused by a disconnected cannula/catheter, which may in turn lead to a blood loss and develop a hazardous situation for the patient within a short time. However, the standards also recognize that certain clinical tasks, such as pressure zeroing and blood sampling, may also result in this alarm, since the tasks may cause the above-mentioned alarm condition to be fulfilled. Nevertheless, high priority alarm is still required in these events since it is regarded that the benefit of a rapid alarm exceeds the disadvantage caused by the false alarms that result from normal clinical procedures.
Although the false alarms may be prevented by inactivation of the alarm functionality or by disabling blood pressure alarm signals, they still are nuisance alarms that require additional measures before and/or after the clinical task that causes the false alarm. That is, if a false alarm is to be avoided, some kind of inactivation of the alarm functionality is needed before the task. Further, restoration of the alarm functionality is normally needed after the task to return to the normal situation. If the false alarm is allowed, additional measures are needed in response to the alarm to return the patient monitor back to normal state.
Thus, normal clinical workflow may include several tasks that drop the measured blood pressure temporarily to zero. Such occasions include zeroing and/or leveling of the pressure transducer and taking blood samples, for example. The requirement of an alarm in response to a sudden blood pressure drop leads in connection with these tasks to situations in which the nursing staff needs to take complicated additional measures either to avoid a false alarm or to acknowledge a false alarm, since the patient monitor has no intrinsic intelligence to sort out alarms that are caused intentionally by the nursing staff. This complicates the work of the nursing staff, especially as the high priority alarm may be persistent and may thus, depending on the alarm logic, reappear after a while.